I don't like the theory that Eris could be Helion's son too.
I know many like it and I understand why.
I prefer a narrative where your origins don't have to doom and define you. That's the point of his character.
It's much more poetic if Eris is Beron's son, but instead of growing into his cruelty, he grows out of his cruelty. Because he feels it upon himself and others, every single day. More poetic if Eris decides to honor the gentleness of his mother instead.
More poetic if Eris realizes he has a lot from his father and not all of it has to be negative. Some of it is assertiveness, determination, fierceness.
There's beauty in coming to terms with your origins, your upbringing. And deciding it does not have to define you forever. There's beauty in recognizing the good and the ugly and deciding you can shape your own self from that.
Eris does not have to be Helion's son to be good! And that's his character's point! That he didn't let his father win and that he chose to be his own person! And is still trying to be and probably has a bunch of guilt and identity issues! But still he doesn't give in!!
He also doesn't need to be Helion's son to be truly loved by his mother! That is also the point of his character! To see that he chose to prioritize and hold onto his mother's caring nature. That he could've grown into a cruel sexist but he would never do that to her. That he would never close his eyes to her suffering!
Wishing him to be Helion's son, empties the meaning of his character. And devalues all of his internal and external suffering and efforts. It also supports an awful genetic determinism.
Being Beron's son and deciding to break from Beron's mold, is the beauty of Eris Vanserra!!